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Fire alarm commissioning and electrical test tools on a workbench

Estimate a rectangular detector grid

Detector Spacing Calculator

Use radial coverage for smoke or heat detectors and a pitched-ceiling allowance.

Method context

BS 5839-1:2025 Clause 21.2

The implementation follows the current Swift calculator in the Fire Regs Pro project. It is an estimate for revision and preliminary checking.

Check before use: Confirm the current standard, project specification, manufacturer data, environmental derating and actual site measurements. A browser result is not a design certificate.